Many risky behaviors occur with higher frequency in adolescence than in any other stage of life--teens are more likely to binge drink, have casual sex partners, engage in violent behavior, commit crimes, and be involved in serious automobile accidents than either children or adults. Clearly, this adolescent surge in risky dangerous behavior is an important public health concern. Moreover, some antecedent risk factors and consequences are unique to girls. For example, pubertal maturation begins earlier in girls than boys, the specific hormonal changes at puberty differ for girls and boys, some of the psychological and social stressors that contribute to substance abuse and sexual risk-taking appear different, and some negative consequences (such as unplanned pregnancy) are unique to females. Thus, the proposed program of research seeks to clarify the ways in which individual and contextual factors interact to predict risk-taking in adolescent girls. Based on a social neuroscience perspective of adolescent risk-taking, the specific aims of this multi-level project are to (1) investigate the role of sensation seeking in explaining the relationship between pubertal maturation and risk-taking behavior in girls; (2) understand the role of pubertal maturation in influencing girls' sensitivity to social context and resulting risk-taking behavior; nd (3) examine the influence of sensation seeking on girls' risk-taking behavior given the social context. An experimental design will be utilized to examine the research questions within the context of a larger interdisciplinary project. Long-term goals include examining sex differences, longitudinally investigating risk-taking trajectories in multiple domains, exploring hormonal and socio-emotional mechanisms, and developing behavioral methodology to understand complex causal processes. This program of research has major implications for the prevention of substance abuse, sexual risk-taking, and other harmful risky behaviors. A deeper more mechanistic understanding of the interactions between biological, behavioral, and social context interactions leading to risk-taking could provide targets for early intervention programs aimed specifically at girls at particular windows of maturation. The proposed program of research will be enriched through courses in adolescent health, cognitive development, substance abuse, advanced statistical methods, and the responsible conduct of research, as well as multidisciplinary consultations and conference presentations.